NMSU engineering, Extension service pair to demonstrate agricultural use of solar power

For the more than 25,000 farms spread across the rural landscape in New Mexico, electrical power isn't always readily available. Windmills have long been the traditional source of pulling water from wells at remote agricultural outposts, but now, solar panels may be popping up in place of these icons of the American West.

Associate professor Craig Ricketts supervised the work of three mechanical engineering technology seniors who designed and built a solar-powered water pump for Cooperative Extension Service officers to use for field demonstrations. (NMSU photo by Darren Phillips)

New Mexico State University's College of Engineering and the Cooperative Extension Service are teaming up to show New Mexico's farmers and ranchers how they can use alternative energy in their business. Extension officers can now provide live demonstrations with a portable solar-powered water pump.

"There are a lot of producers looking for alternative power options," said Bruce Hinrichs, associate director of the Cooperative Extension Service. "It's difficult for them to know where to start when they are considering new technologies."

Tom Jenkins, professor of engineering technology and head of the department's renewable energy program, has been working with the extension service to produce training presentations explaining the use of renewable energy sources in agricultural applications. Taking the idea further, extension officers wanted to be able to demonstrate to the agricultural community in the state how solar power could be used to pump well water.

Jenkins, acting as a client, presented a group of mechanical engineering technology students with the problem.

Three students took on the problem as their senior capstone project in the spring 2011 semester. Senior capstone design courses are the culmination of the engineering curriculum at NMSU, requiring students to utilize knowledge and skills acquired throughout their coursework.

Under the tutelage of Craig Ricketts, associate engineering technology professor, Cody Anderson, Felicia Costales and Andres Galvan designed and built a portable demonstration unit that could be taken into the field.

The unit consists of a rolling cart outfitted with a small solar panel that collects heat energy from sunlight and converts it to electricity. The electricity powers a high-pressure submersible pump in a 50-gallon storage vessel. The pump is equipped with a sophisticated control box that optimizes the power needed to control the speed of the pump. Meters show the current and voltage produced by the solar panel and used by the pump.

"A major engineering challenge of this project was for the students to come up with a method to simulate different depths of water in a portable unit," said Jeff Beasley, engineering technology and surveying engineering department head.

The students incorporated a valve to control water pressure so the unit can simulate pumping from depths up to 400 feet, using mathematical equations to determine the correlation between water pressure and depth.

"The depth of water in the state is all over the scale, anywhere from 10 to 1,000 feet," said Craig Runyan, associate in Extension Plant Services. "Four hundred feet is pushing the limit for solar, but technology is catching up fast. There are a lot of wells 600-700 feet deep on the eastern side of the state. It's not unreasonable for a conventional windmill to lift water down 700 feet, but it takes quite a while. It really depends on how much flow you need."

At the same time, fellow engineering technology students Lloyd Vigil and Christian Garces were working to develop a spreadsheet tool that could be used by potential clientele of solar water pump systems.

"Users can enter information about the depth of their well, if it will be used for livestock and what type of livestock. The system will recommend a hardware layout for their given application," said Ricketts. "The spreadsheet will recommend the volume of water needed, how much storage will be needed as reserve for cloudy days, how many panels will be needed, pump and pipe size."

The spreadsheet also has an economic component that will help estimate how much a system might cost.

While the market is pretty evenly split between wind and solar used to draw water from wells in New Mexico, said Runyan, producers are all looking for alternatives to the high cost of fuel.

"It's really a personal preference. Wind and solar are cost competitive, but solar may be safer and easier to work with?nobody likes climbing towers. And while wind mills are capable of producing more water, the sun is more consistent and you may end up with more water if you can store it," said Runyan.

These projects and the development of other engineering-based educational materials arose after the Cooperative Extension Service surveyed their officers serving the state's 33 counties about what kind of engineering assistance is needed by their clientele. The response was alternative sources of energy technology that would help them address the challenges associated with the availability of water.

"It's a great avenue for us to help fulfill an increasing need of our clientele," said Jon Boren, associate dean and assistant director of the Cooperative Extension Service. "Using expertise from the College of Engineering for alternative energy technologies, extension has the network to deliver new choices to our clientele.We have an extensive network and the College of Engineering has the expertise."